See, here is your problem with this Buzz, you are thinking there is a problem when there is not, all engines run at different oil PSI numbers, what is high for one engine is normal for another.
Land Rover uses a high volume low PSI oil pump, all engines are different.
My Duramax with over 200k runs at ~25PSI when hot at 60mph, at hot idle it is at ~10PSI.
Cold idle is almost 50PSI.
Perfectly normal for that engine with those miles.
Oil brand and weight makes a huge difference too.
He is perfectly fine with his oil PSI numbers, switching to the thicker oil will help his numbers, but he is perfectly fine.
I do not understand all of this "doom and gloom", as long as the oil light is not coming on or the oil PSI is at 10 while driving things are just fine.

 

I guess we can agree (A.) that I am too conservative; (B.) that if it is hot outside he can run thicker oil (within spec of book), and (C.) that if his normal psi is very low with the thicker oil or varies for no good reason it might be time to look at the oil pump.

I scanned the RAVE, and as usual, Spike is right, even among similar Rover engines specs vary. For example, a D2 is spec'd for 50 PSI @2000 rpm, but the pressure relief valve is spec'd for the same value; might be a typo somewhere. So here is the list, from the general data list for each:

94 Defender.............. 30 - 40 @ 2400
89 Range Rover......... 30 - 40 @ 2400
Disco 1 3.9 ............. 40 @2500
Disco 1 4.0 .............. 30 - 40 @ 2500 (GEMS)
95 Range Rover .........30 - 40 @ 2400
99 Range Rover .........50 @ 2000
Disco 2 ....................50 @ 2000, 10 minimum.
02 Range Rover ........ 43.5 @3500, 7 minimum (!)
Freelander V6............ 43.5 @ 3000, 14.5 minimum

However it is important to note that the minimum pressure at idle is usually just above the PSI for the oil warning light. If your have a bad oil pump, you can get low numbers at other ranges, and the light won't come on unless it is seriously low. Flickering light while driving is a big issue, because you are at 6-8 PSI when you should be much higher. After market oil gauge is a good thing to have.

And it would appear that for a D2 the 30 PSI or so when rolling down the highway is low.

pass the Lucas.....

 

The oil pump is not the only piece to the oil pressure equation. Don't want people believing that if the reading is low, the only thing one must do is put in a new pump. If a new pump doesn't make a difference, don't blame the pump. It just may be time for an engine overhaul.

 

Call me crazy, call me lazy, tell me I dont give a sh!it, but as long as it is not making noise and/or the oil light is not coming on its all good.
No problems with running a actual oil PSI gauge, I would like one if I could make it look OEM, but its just a stupid truck that can be fixed or replaced.
To much time is spent worrying about things that make no matter in my opinion.
If oil pressure numbers are to low and do not change with a different oil there could be lots of potential problems which could even be the oil, even a thicker oil if of a lesser quality or good oil if it is old can give low oil PSI.

I am far from a expert but...is the oil light coming on? Is it making noise? No? Then dont worry about it, go play with your kids, take your wife out to dinner, watch tv, lifes short, live it.

 

That is great info, thank you for looking it up.

 

Spike,

I am confused about the D2 vs D1 PSI rating, don't the 4.0's share the same short block?

 

Yes, yes they do.
I have no idea why the numbers are different, better quality motor oil maybe?
Oil's today are better than just 10 yrs ago so maybe? I dont know, I really dont.

 

Lets build a theory on this Buzz.
Same block, same oil pump, but different oil numbers?
Why?
Oil Pump Gear Kit | Land Rover Engine Parts at RoverParts.com
But yet DII's seem to have more oil PSI problems than DI's, why?
I am going to shoot a e-mail to a engineer friend of mine and see if he has any input.

 

From RAVE test procedures for oil pump:

4.

+

6.

8.

+

big end bearings.

Would these bearings be different from D1 to D2?

Oil cooler? Some D2 have it, others don't, and all D1 have one, but it is a different model.

It is not un-heard of to have typos in a large document. Here is one from the warning lights section of the D1 electrical manual:

The transmission/transfer box oil temperature
warning light is grounded by the Automatic
Transmission Oil Temperature Switch (X108) when
the temperature of the transmission fluid exceeds
130

°C (266°F). The warning light is also grounded
by the Transfer Box Oil Temperature Switch (X174)
when the temperature of the transfer box fluid
exceeds 145°C (266°F). On Australian vehicles the
warning light is grounded by a 3 second timer as a
bulb check.

Obviously 130 and 145 degrees C can't both equal 266 degrees F.

Now from the D1 shop manual, oil pressure test:

At a steady engine speed of 2500 rev/min -
engine oil pressure reading should be - 2.75 bar

(40 lbf/in 2).

So a D2 is supposed to make 50 PSI at 2000 rpm, and a D1 does 40 PSI at 2500 ??

 

Nope, same bearings, same oil pump.

Main Bearing Set Std . 4.0/4.6 | Land Rover Engine Parts at RoverParts.com

I posted the oil pump already in this thread.